The Broadgate Exchange House, London, UK

In order to span 78 m over congested railway tracks, the Broadgate Exchange House in northeast London combines the system concepts of a bridge with those of an office building. The site faces the Liverpool Street Station train shed, an historic structure of exposed iron and steel. Design objectives included unobstructed operations for the trains and a structure that would both complement the historically significant train shed and act as a centerpiece whose articulated structural form would contrast with neighbouring stone and glass-clad buildings. The innovative combination of systems in the Broadgate Exchange House, together with a rigorous application of rational fire engineering, resulted in a structure that expresses a new architectural vocabulary in steel construction.